Lubricating oil containing a wax pour point and cloud point suppresser



LUBRICATING OIL CONTAINING A WAX POUR FONT AND CLOUD POINT 'SUPPRESSER I Herman J. Zoeller, Union, N.J., assignor to EssoReseai-ch and Engineering Company, a corporationrof Delaware No Drawing. Application August 6, 1056 Serial No. 602,441

4 Claims. (Cl. 208-19) The present invention relates to improvements in the cloud and haze properties of lubricating oils, diesel oils, transformer oils, and similar petroleum'oils which are often used or stored at low temperatures. More particularly, the present invention relates to the reduction of the haze and cloud points of these oils by a new and improved incorporation of an inhibitor therein.

The unsatisfactory performance of lubricating oils and diesel fuels at cold temperatures and-incoldclimates is a problem that has been with the petroleum industry a long time. The problem hasbeen tracedto small amounts of wax in the oils. Below a critical temperature, the cloud point of the oil, the Wax'begins to solidify. If the oil is a diesel fuel, the solids thus-formed may block filters in the-fuel system and eventually cause fuel starvation of the engine. In the case of lubricating'oils, the precipitated wax increases the viscosityof the oil and makes proper lubrication difiicult.

Conventional dewaxing operations, solvent dewaxing processes for example, are not always feasible nor satisfactory. These are expensive processing steps and their costs often cannotbe justified. Many refineries produce lubricating oils from crudes having .low wax contents,-such as naph thenic crudes. The amountof Wax in such oils is not. enough to warrant a conventional dewaxing treatment,

which necessitates the use of expensive solvents, compressors, refrigerants, filtration equipment and thelike. Yet the small amount 'of waxspresent, of'the order of up to 3%, at +25 F. pour point is enough to disqualify the lubes as low cold test oils. The same is true for diesel fuels.

Other processing steps, such as clay treating, acid treating, and phenol extraction do not have a significant effect on the haze point.

As little as 0.1 to 0.5% of suspended wax crystals in low cold test lubes causes haze, and only 0.15% of wax will raise the haze point 30 F.

Hydrocarbon oils which contain waxy constituents thus often lose their limpidity due to the separation of these solid wax particles, which appear either in the form of a cloud within the oil or as a more or less crystalline pre cipitate which may remain dispersed throughout the oil. Frequently the separated wax collects on the walls of the container, particularly near the surface of the oil. Such separation often occurs at temperatures which are sub- 2 ,90,322 Patented Aug. 18, 1959 lubricating or fuel system may become obstructed. This separation of solid wax is manifested both-in the formation of clouds of dispersedprecipitate and in the formation of surface wax.

It is an object of the present invention to provide a process for reducing or preventing the separation of such particles of wax by the addition to the oil of an additive that does not itself contribute to the formation of wax and cloud.

Other objects and advantages of the present invention will be readily apparent from the more detailed description of the invention hereinafter.

It has now been found that excellent cloud and haze reduction in wax-containing oils may be obtained by adding to these oils small amounts of narrow-boiling, low-melting point hydrocarbon mixtures of a definite composition. More specifically, this reduction is obtained by adding small amounts, .001 to..02% by Weight, of parafiinwax melting in the range of about 100 to 1.l8--F. which consists of a substantial proportion of non-normal pa-raflin waxes. Still more specifically, .para'fiin Wax compositions melting in the range of 100 toll-8 .F. andcomposecl of from about to 55% normalparaflins inthe C C molecular weight range, 20% to 25% isoparaflins, and about 20% to 25% naphthenes are especially effective in reducing cloud points oflubricating oils, even whenadded in amounts as low as from 0.001 to 0.005% by weight.

It is customary to add certain compositions to lubricating oils to lower the congealing, or pour point of the oil. These additives, such as the condensationproducts of aromatics and long chain alkyl' halides, generally have no effect upon the cloud or haze point of an oil, and sometimes even raise the latter. The inhibitor composition of the present invention, however, has no particular effect upon the pour point of the oil, but has a marked effect in preventing or retarding the separation of finely divided wax particles. The cloud point inhibitor of the present invention, therefore, may be employed in'compositions with conventional 'pour depressants.

The cloud inhibitor may be added to the oils at elevated temperatures. It is often desirable to dissolve 'a large amount of the inhibitor in a small quantity of oil and then toadd this concentrate-to'the'rnain body of oil at ordinary temperatures. In general, because ofthe'high effectiveness of the inhibitor, about .001 to .005% by weight is employed. 'Higherconcentrations tend'tjo instantially above the congealing temperature, or pour point 0 P n ains ese constituents in the ratio of apof the oil, with the result that small constrictions in a proximately 21-1. Other compositions non-reactive to point, high molecular weight normal paraflins.

urea and containing less n-paraflins, and more isoparaflins and naphthenes, have been found not to be effective as cloud point depressants. Similarly, compositions having a greater proportion of normal paraifins tend to raise the pour point.

To illustrate the effectiveness of the haze and cloud inhibitors of the present invention, the following examples are offered.

In Table I below, there is shown the inspection and composition of the inhibitors of the present-invention. For comparative purposes, the effects of four mixtures are shown, designated respectfully by A, B, C and D. In column A there is shown a commercial grade paraffin wax prepared by solvent de-oiling of a lubricating oil distillate. The source of wax is such that there is at least'l4 to 16 weight percent of non-normals therein. The total wax A was vacuum distilled'to 10% bottoms to concentrate the non-normals. Then the bottoms were treated with urea to separate the high melting The nonreactive material is labeled Inhibitor B.

A separate portion of the total wax A was solvent re-crystallized at +65 F. to remove the high melting normal paraflins as a wax cake, while the filtrate contains most of the low melting point normal and nonnormal paraffins. The filtrate wax, after stripping to remove solvent, was urea adducted to separate normal from non-normal paraffins. The non-reactive material is designated Inhibitor C.

The total wax A was urea adducted directly with no intermediate processing sequence to separate the high melting, high molecular weight paraffins. The non-reactive material is designated Inhibitor D.

In all of the urea treats above, similar conditions of treat, temperature, proportions, and the like obtained. Each inhibitor is the urea-non-reactive material except A, which is the original wax base stock. The lube base stock itself is an extracted low cold test lube oil from coastal-naphthenic type crude. The urea adduction experiments for removal of highly paraffinic components employed 300 weight percent treats at 160 to 165 F. in solvent solution with water as promoter.

TABLE I Cloud point reduction of lube oil PART A.PREPARATION AND INSPECTION OF INHIBITORS I PART B.EFFEOTIVENESS OFINHIBITORS AS CLOUD POINT .DEPRESSANTS Inhibitor Weight ASTM ASTM percent Pour, F. Cloud, F.

N one +20 +48 0. 001 +20 +32 0. 005 +20 +36 0. 2 +30 +54 0. 001 +10 +32 0.005 +20 +32 0. 2 +25 +50 0.001 +15 +20 0. 005 +15 +22 0. 2 +25 +48 0. 001 +20 +22 0. 005 +20 +22 0. 2 +25 +52 The superiority of the composition of the present invention as a cloud point inhibitor is clearly shown when compared with cloud point inhibitors suggested by the art. One such inhibitor is montan wax. The latter requires an initial bleaching operation to make it suitable for incorporation into wax compositions. In Table II below, is shown the efiect of adding small amounts of montan wax to a raifinate obtained by extracting low cold test lubricating oil from a Tia Juana naphthenic type crude. It will be noted that, in the concentrations in which the additive of the invention is efiective, substantially no cloud point reduction was realized with the montan wax.

TABLE II Inhibitor Weight ASTM AS'IM percent Pour, F. Cloud, F.

an it; itfi Bleached Montan Wax 0:005 +20 +46 What is claimed is:

1. A hydrocarbon oil to which has been added as a haze and cloud point suppressor from about 0.001% to about 0.02% by weight of a petroleum wax composition melting in the range between about F. and about 118 F., said composition containing about 45 to 55 mol. percent of normal paraffin waxes, about 15 to 25 mol. percent of isoparafiin waxes, and about 15 to 25 mol. percent of naphthenic waxes.

2. An oil as defined by claim 1 wherein said wax composition contains normal paraflin, isoparaflin and naphthenic waxes in a mol. ratio of about 2/1/1.

3. An oil as defined by claim 1 wherein said wax com.- position is present in a concentration of from. about 110.01% to about 0.005% by weight.

4. An oil as defined by claim 1 wherein said wax composition is employed in conjunction with a pour point depressant.

References Cited in the file of this patent UNITED STATES PATENTS 2,671,051 Moore Mar. 2, 1954 

1. A HYDROCARBON OIL TO WHICH HAS BEEN ADDED AS A HAZE AND CLOUD POINT SUPPRESSOR FROM ABOUT 0.001% TO ABOUT 0.02% BY WEIGHT OF A PETROLEUM WAX COMPOSITION MELTING IN THE RANGE BETWEEN ABOUT 100*F. AND ABOUT 118*F., SAID COMPOSITION CONTAINING ABOUT 45 TO 55 MOL. PERCENT OF NORMAL PARAFFIN WAXES, ABOUT 15 TO 25 MOL. PERCENT OF ISOPARAFFIN WAXES AND ABOUT 15 TO 25 MOL. PERCENT OF NAPHTHENIC WAXES. 